U.S. patent application number 15/519961 was filed with the patent office on 2018-10-18 for pixel driver circuit, pixel driving method, display panel and display device.
This patent application is currently assigned to BOE TECHNOLOGY GROUP CO., LTD.. The applicant listed for this patent is BOE TECHNOLOGY GROUP CO., LTD.. Invention is credited to Zhanjie MA.
Application Number | 20180301092 15/519961 |
Document ID | / |
Family ID | 55505963 |
Filed Date | 2018-10-18 |
United States Patent
Application |
20180301092 |
Kind Code |
A1 |
MA; Zhanjie |
October 18, 2018 |
PIXEL DRIVER CIRCUIT, PIXEL DRIVING METHOD, DISPLAY PANEL AND
DISPLAY DEVICE
Abstract
A pixel driver circuit includes a driving transistor, a first
storage capacitor, a second storage capacitor, a threshold
compensation unit, a data writing unit and a light-emitting control
unit. The threshold compensation unit is configured to control the
driving transistor to be turned on at a threshold compensation
stage and discharge toward a resetting voltage line until the
driving transistor is turned off. The data writing unit is
configured to write a data voltage into a gate electrode of the
driving transistor at a data writing stage. The light-emitting
control unit is configured to enable the driving transistor to be
turned on at a light-emitting stage, so as to drive a
light-emitting element to emit light.
Inventors: |
MA; Zhanjie; (Beijing,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BOE TECHNOLOGY GROUP CO., LTD. |
Beijing |
|
CN |
|
|
Assignee: |
BOE TECHNOLOGY GROUP CO.,
LTD.
Beijing
CN
|
Family ID: |
55505963 |
Appl. No.: |
15/519961 |
Filed: |
August 29, 2016 |
PCT Filed: |
August 29, 2016 |
PCT NO: |
PCT/CN2016/097184 |
371 Date: |
April 18, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G 2310/0262 20130101;
G09G 3/3233 20130101; G09G 3/3258 20130101; G09G 2300/0819
20130101; G09G 2310/061 20130101; G09G 2320/045 20130101; G09G
2300/0861 20130101; G09G 2300/0852 20130101; G09G 2310/0251
20130101 |
International
Class: |
G09G 3/3258 20060101
G09G003/3258 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 4, 2016 |
CN |
201610003695.8 |
Claims
1. A pixel driver circuit, comprising a driving transistor, a first
storage capacitor, a second storage capacitor, a threshold
compensation unit, a data writing unit and a light-emitting control
unit, wherein a gate electrode of the driving transistor is
connected to a first end of the first storage capacitor, and a
first electrode of the driving transistor is connected to a second
end of the first storage capacitor; a first end of the second
storage capacitor is configured to receive a first power source
voltage, and a second end of the second storage capacitor is
connected to the second end of the first storage capacitor; the
threshold compensation unit is configured to, at a threshold
compensation stage of each display period, control the gate
electrode of the driving transistor to receive a reference voltage
and enable a second electrode of the driving transistor to be
connected to a resetting voltage line, so as to enable the driving
transistor to be turned on and discharge toward the resetting
voltage line until the driving transistor is turned off; the data
writing unit is configured to, at a data writing stage of each
display period, write a data voltage into the gate electrode of the
driving transistor; the light-emitting control unit is configured
to, at a light-emitting stage of each display period, control the
first electrode of the driving transistor to receive the first
power source voltage and enable the second electrode of the driving
transistor to be connected to a light-emitting element, so as to
enable the driving transistor to be turned on and drive the
light-emitting element to emit light; a total amount of charges
stored in the first storage capacitor and a total amount of charges
stored in the second storage capacitor at the threshold
compensation stage is equal to those at the data writing stage; an
amount of charges stored in the first storage capacitor at the data
writing stage is equal to an amount of charges stored in the first
storage capacitor at a light-emitting control stage; within each
display period, the threshold compensation stage further comprises
a resetting stage; the threshold compensation unit is further
configured to, at the resetting stage, control the gate electrode
of the driving transistor to receive the reference voltage and
control the second electrode of the driving transistor to receive a
resetting voltage; the light-emitting control unit is further
configured to, at the resetting stage, control the first electrode
of the driving transistor to receive the first power source voltage
and enable the second electrode of the driving transistor to be
connected to the light-emitting element and the driving transistor
is in an amplified state or a saturation state at the resetting
stage.
2. (canceled)
3. The pixel driver circuit according to claim 1 wherein the
light-emitting element comprises an organic light-emitting diode
(OLED), an anode of the OLED is connected to the second electrode
of the driving transistor through the light-emitting control unit,
and a cathode of the OLED is configured to receive a second power
source voltage; and at the resetting stage, a difference between
the resetting voltage from the resetting voltage line and the
second power source voltage is smaller than an on-state threshold
voltage of the OLED.
4. The pixel driver circuit according to claim 1, wherein the
threshold compensation unit comprises a first compensating
transistor and a second compensating transistor; a gate electrode
of the first compensating transistor is configured to receive a
resetting control signal, a first electrode of the first
compensating transistor is connected to the second electrode of the
driving transistor, and a second electrode of the first
compensating transistor is connected to the resetting voltage line;
and a gate electrode of the second compensating transistor is
configured to receive the resetting control signal, a first
electrode of the second compensating transistor is connected to the
gate electrode of the driving transistor, and a second electrode of
the second compensating transistor is configured to receive the
reference voltage.
5. The pixel driver circuit according to claim 3, wherein the
threshold compensation unit comprises a first compensating
transistor and a second compensating transistor; a gate electrode
of the first compensating transistor is configured to receive a
resetting control signal, a first electrode of the first
compensating transistor is connected to the second electrode of the
driving transistor, and a second electrode of the first
compensating transistor is connected to the resetting voltage line;
and a gate electrode of the second compensating transistor is
configured to receive the resetting control signal, a first
electrode of the second compensating transistor is connected to the
gate electrode of the driving transistor, and a second electrode of
the second compensating transistor is configured to receive the
reference voltage.
6. The pixel driver circuit according to claim 4, wherein the first
compensating transistor and the second compensating transistor are
both P-type transistors.
7. The pixel driver circuit according to claim 1, wherein the data
writing unit comprises a data writing transistor, a gate electrode
of the data writing transistor is configured to receive a scanning
signal, a first electrode of the data writing transistor is
connected to the gate electrode of the driving transistor, and a
second electrode of the data writing transistor is configured to
receive a data voltage.
8. The pixel driver circuit according to claim 7, wherein the data
writing transistor is a P-type transistor.
9. The pixel driver circuit according to claim 5, wherein the data
writing unit comprises a data writing transistor, a gate electrode
of the data writing transistor is configured to receive a scanning
signal, a first electrode of the data writing transistor is
connected to the gate electrode of the driving transistor, and a
second electrode of the data writing transistor is configured to
receive a data voltage.
10. The pixel driver circuit according to claim 1, wherein the
light-emitting control unit comprises a first light-emitting
control transistor and a second light-emitting control transistor;
gate electrode of the first light-emitting control transistor is
configured to receive a light-emitting control signal, a first
electrode of the first light-emitting control transistor is
configured to receive the first power source voltage, and a second
electrode of the first light-emitting control transistor is
connected to the first electrode of the driving transistor; and a
gate electrode of the second light-emitting control transistor is
configured to receive the light-emitting control signal, a first
electrode of the second light-emitting control transistor is
connected to the second electrode of the driving transistor, and a
second electrode of the second light-emitting control transistor is
connected to the light-emitting element.
11. The pixel driver circuit according to claim 10, wherein the
first light-emitting control transistor and the second
light-emitting control transistor are both P-type transistors.
12. The pixel driver circuit according to claim 9, wherein the
light-emitting control unit comprises a first light-emitting
control transistor and a second light-emitting control transistor;
a gate electrode of the first light-emitting control transistor is
configured to receive a light-emitting control signal, a first
electrode of the first light-emitting control transistor is
configured to receive the first power source voltage, and a second
electrode of the first light-emitting control transistor is
connected to the first electrode of the driving transistor; and a
gate electrode of the second light-emitting control transistor is
configured to receive the light-emitting control signal, a first
electrode of the second light-emitting control transistor is
connected to the second electrode of the driving transistor, and a
second electrode of the second light-emitting control transistor is
connected to the light-emitting element.
13. A pixel driving method applied to the pixel driver circuit
according to claim 1, comprising: at a threshold compensation stage
of each display period, controlling, by a threshold compensation
unit, a gate electrode of a driving transistor to receive a
reference voltage, and enabling a second electrode of the driving
transistor to be connected to a resetting voltage line, so as to
enable the driving transistor to be turned on and discharge toward
a start voltage line until the driving transistor is turned off; at
a data writing stage of each display period, writing, by a data
writing unit, a data voltage into the gate electrode of the driving
transistor; and at a light-emitting stage of each display period,
enabling, by a light-emitting control unit, a first electrode of
the driving transistor to be driven by a first power source
voltage, and enabling the second electrode of the driving
transistor to be connected to a light-emitting element, so as to
enable the driving transistor to be turned on and drive the
light-emitting element to emit light, wherein a total amount of
charges stored in a first storage capacitor and charges stored in a
second storage capacitor at the threshold compensation stage is
equal to that at the data writing stage; and an amount of charges
stored in the first storage capacitor at the data writing stage is
equal to an amount of charges stored in the first storage capacitor
at the light-emitting control stage.
14. The pixel driving method according to claim 13, wherein within
each display period, the threshold compensation stage further
comprises a resetting stage; the pixel driving method further
comprises, at a resetting stage of each display period,
controlling, by the threshold compensation unit, the gate electrode
of the driving transistor to receive the reference voltage and
enabling the second electrode of the driving transistor to be
connected to the resetting voltage line, and controlling, by the
light-emitting control unit, the first electrode of the driving
transistor to receive the first power source voltage and enabling
the second electrode of the driving transistor to be connected to
the light-emitting element; and the driving transistor is in an
amplified state or a saturation state at the resetting stage.
15. A pixel driving method applied to the pixel driver circuit
according to claim 12, comprising: at a threshold compensation
stage of each display period, enabling a light-emitting control
signal and a scanning signal to be turn-off signals, and enabling a
resetting control signal to be a turn-on signal, so as to enable a
resetting voltage line to output a resetting voltage at a low
level, enable a first light-emitting control transistor and a
second light-emitting control transistor to be turned off, enable a
first compensating transistor and a second compensating transistor
to be turned on, and enable charges at a connection node between a
first storage capacitor and a second storage capacitor to be
discharged toward the resetting voltage line through a driving
transistor and the first compensating transistor until a potential
at a source electrode of the driving transistor is sufficient low
to turn off the driving transistor; at a data writing stage of each
display period, enabling the light-emitting control signal and the
resetting control signal to be turn-off signals, and enabling the
scanning signal to be a turn-on signal, so as to enable the first
light-emitting control transistor and the second light-emitting
control transistor to be turned off, enable the first compensating
transistor and the second compensating transistor to be turned off,
enable a data writing transistor to be turned on to write a data
voltage into a gate electrode of the driving transistor, and enable
the connection node between the first storage capacitor and the
second storage capacitor to be in a floating state, a total amount
of the charges stored in the first storage capacitor and the
charges stored in the second storage capacitor at the threshold
compensation stage being equal to that at the data writing stage;
and at a light-emitting stage of each display period, enabling the
scanning signal and the resetting control signal to be turn-off
signals to turn off the first compensating transistor, the second
compensating transistor and the data writing transistor, and
enabling the light-emitting control signal to be a turn-on signal,
so as to enable the first light-emitting control transistor and the
second light-emitting control transistor to be turned on, enable a
light-emitting element to be electrically connected to a second
electrode of the driving transistor, enable a first power source
voltage to be written into a connection node among a first
electrode of the driving transistor, the first storage capacitor
and the second storage capacitor, enable a first end of the second
storage capacitor to receive the first power source voltage, and
enable a connection node between the first storage capacitor and
the gate electrode of the driving transistor to be in a floating
stage, an amount of the charges stored in the first storage
capacitor at the data writing stage being equal to an amount of the
charges stored in the first storage capacitor at the light-emitting
control stage so that a current flowing through the driving
transistor at the light-emitting stage is merely associated with
the data voltage, a capacitance of the first storage capacitor and
a capacitance of the second storage capacitor.
16. The pixel driving method according to claim 15, wherein within
each display period, the threshold compensating stage further
comprises a resetting stage, and the pixel driving method further
comprises, at the resetting stage of each display period, enabling
the light-emitting control signal and the resetting control signal
to be turn-on signals, and enabling the scanning signal to a
turn-off signal, so as to enable the first light-emitting control
transistor and the second light-emitting control transistor to be
turned on, enable the first compensating transistor and the second
compensating transistor to be turned on, enable the data writing
transistor to be turned off, enable the light-emitting element to
be connected to the second electrode of the driving transistor,
enable the resetting voltage to be written into the second
electrode of the driving transistor, and enable the driving
transistor to be in an amplified state or a saturation state.
17. The pixel driving method according to claim 16, wherein the
light-emitting element includes an organic light-emitting diode
(OLED), an anode of the OLED is connected to the second electrode
of the driving transistor through the light-emitting control unit,
and a cathode of the OLED is configured to receive a second power
source voltage, at the resetting stage, a difference between the
resetting voltage from the resetting voltage line and the second
power source voltage is smaller than an on-state threshold voltage
of the OLED.
18. A display panel comprising the pixel driver circuit according
to claim
19. A display device comprising the display panel according to
claim 18.
20. A pixel driving method applied to a pixel driver circuit, the
pixel driver circuit comprising a driving transistor, a first
storage capacitor, a second storage capacitor, a threshold
compensation unit, a data writing unit and a light-emitting control
unit, wherein a gate electrode of the driving transistor is
connected to a first end of the first storage capacitor, and a
first electrode of the driving transistor is connected to a second
end of the first storage capacitor; a first end of the second
storage capacitor is configured to receive a first power source
voltage, and a second end of the second storage capacitor is
connected to the second end of the first storage capacitor; the
threshold compensation unit is configured to, at a threshold
compensation stage of each display period, control the gate
electrode of the driving transistor to receive a reference voltage
and enable a second electrode of the driving transistor to be
connected to a resetting voltage line, so as to enable the driving
transistor to be turned on and discharge toward the resetting
voltage line until the driving transistor is turned off; the data
writing unit is configured to, at a data writing stage of each
display period, write a data voltage into the gate electrode of the
driving transistor; the light-emitting control unit is configured
to, at a light-emitting stage of each display period, control the
first electrode of the driving transistor to receive the first
power source voltage and enable the second electrode of the driving
transistor to be connected to a light-emitting element, so as to
enable the driving transistor to be turned on and drive the
light-emitting element to emit light; a total amount of charges
stored in the first storage capacitor and a total amount of charges
stored in the second storage capacitor at the threshold
compensation stage is equal to those at the data writing stage; and
an amount of charges stored in the first storage capacitor at the
data writing stage is equal to an amount of charges stored in the
first storage capacitor at a light-emitting control stage, the
pixel driving method comprising: at a threshold compensation stage
of each display period, controlling, by a threshold compensation
unit, a gate electrode of a driving transistor to receive a
reference voltage, and enabling a second electrode of the driving
transistor to be connected to a resetting voltage line, so as to
enable the driving transistor to be turned on and discharge toward
a start voltage line until the driving transistor is turned off; at
a data writing stage of each display period, writing, by a data
writing unit, a data voltage into the gate electrode of the driving
transistor; and at a light-emitting stage of each display period,
enabling, by a light-emitting control unit, a first electrode of
the driving transistor to be driven by a first power source
voltage, and enabling the second electrode of the driving
transistor to be connected to a light-emitting element, so as to
enable the driving transistor to be turned on and drive the
light-emitting element to emit light, within each display period,
the threshold compensation stage further comprises a resetting
stage, the pixel driving method further comprises, at a resetting
stage of each display period, controlling, by the threshold
compensation unit, the gate electrode of the driving transistor to
receive the reference voltage and enabling the second electrode of
the driving transistor to be connected to the resetting voltage
line, and controlling, by the light-emitting control unit, the
first electrode of the driving transistor to receive the first
power source voltage and enabling the second electrode of the
driving transistor to be connected to the light-emitting element,
and the driving transistor is in an amplified state or a saturation
state at the resetting stage.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims a priority of the Chinese
patent application No. 201610003695.8 filed on Jan. 4, 2016, which
is incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to the field of display
technology, in particular to a pixel driver circuit, a pixel
driving method, a display panel and a display device.
BACKGROUND
[0003] Currently, in the field of active-matrix organic
light-emitting diode (AMOLED) display, especially in the design of
a large-size substrate, an uneven current may flow through an
organic light-emitting diode (OLED) due to unevenness and
instability of a thin film transistor (TFT) on a back plate during
the processing. In order to compensate for a threshold voltage
(Vth) drift due to the TFT unevenness during the manufacture of the
back plate, and a TFT characteristic drift due to a bias voltage
after the operation for a long time period, an AMOLED compensation
circuit is provided. In the case that the AMOLED tends to be of a
larger size, a load applied to a signal line may increase and
voltage attenuation may occur for a power source signal line, thus
current evenness at a display region may be adversely affected.
[0004] For a conventional OLED compensation circuit, a desired data
driving voltage range may be reduced along with an increase in the
efficiency of a light-emitting element, and this will be beyond a
driving capability of a driver Integrated Circuit (IC). However, it
is unable for a conventional pixel driver circuit to compress the
data at different compression ratios, so it is impossible to raise
the data driving voltage range of the driver IC.
SUMMARY
[0005] A main object of the present disclosure is to provide a
pixel driver circuit, a pixel driving method, a display panel and a
display device, so as to compress data at different compression
ratios, thereby to raise the data driving voltage range of the
driver IC.
[0006] In one aspect, the present disclosure provides in some
embodiments a pixel driver, including a driving transistor, a first
storage capacitor, a second storage capacitor, a threshold
compensation unit, a data writing unit and a light-emitting control
unit. A gate electrode of the driving transistor is connected to a
first end of the first storage capacitor, and a first electrode
thereof is connected to a second end of the first storage
capacitor. A first end of the second storage capacitor is
configured to receive a first power source voltage, and a second
end thereof is connected to the second end of the first storage
capacitor. The threshold compensation unit is configured to, at a
threshold compensation stage of each display period, enable the
gate electrode of the driving transistor to receive a reference
voltage and enable a second electrode of the driving transistor to
be connected to a resetting voltage line, so as to enable the
driving transistor to be turned on and discharged toward the
resetting voltage line until the driving transistor is turned off.
The data writing unit is configured to, at a data writing stage of
each display period, write a data voltage into the gate electrode
of the driving transistor. The light-emitting control unit is
configured to, at a light-emitting stage of each display period,
enable the first electrode of the driving transistor to receive the
first power source voltage and enable the second electrode of the
driving transistor to be connected to a light-emitting element, so
as to enable the driving transistor to be turned on and drive the
light-emitting element to emit light. A total amount of charges
stored in the first storage capacitor and a total amount of charges
stored in the second storage capacitor at the threshold
compensation stage is equal to those at the data writing stage. An
amount of charges stored in the first storage capacitor at the data
writing stage is equal to an amount of charges stored in the first
storage capacitor at the light-emitting control stage.
[0007] In a possible embodiment of the present disclosure, within
each display period, the threshold compensation stage further
includes a resetting stage. The threshold compensation unit is
further configured to, at the resetting stage, enable the gate
electrode of the driving transistor to receive the reference
voltage and enable the second electrode of the driving transistor
to receive a resetting voltage. The light-emitting control unit is
further configured to, at the resetting stage, enable the first
electrode of the driving transistor to receive the first power
source voltage and enable the second electrode of the driving
transistor to be connected to the light-emitting element. The
driving transistor is in an amplified state or a saturation state
at the resetting stage.
[0008] In a possible embodiment of the present disclosure, the
light-emitting element includes an OLED, an anode of which is
connected to the second electrode of the driving transistor through
the light-emitting control unit, and a cathode of which is
configured to receive a second power source voltage. At the
resetting stage, a difference between the resetting voltage from
the resetting voltage line and the second power source voltage is
smaller than an on-state threshold voltage of the OLED.
[0009] In a possible embodiment of the present disclosure, the
threshold compensation unit includes a first compensating
transistor and a second compensating transistor. A gate electrode
of the first compensating transistor is configured to receive a
resetting control signal, a first electrode thereof is connected to
the second electrode of the driving transistor, and a second
electrode thereof is connected to the resetting voltage line. A
gate electrode of the second compensating transistor is configured
to receive the resetting control signal, a first electrode thereof
is connected to the gate electrode of the driving transistor, and a
second electrode thereof is configured to receive the reference
voltage.
[0010] In a possible embodiment of the present disclosure, the data
writing unit includes a data writing transistor, a gate electrode
of which is configured to receive a scanning signal, a first
electrode of which is connected to the gate electrode of the
driving transistor, and a second electrode of which is configured
to receive a data voltage.
[0011] In a possible embodiment of the present disclosure, the
light-emitting control unit includes a first light-emitting control
transistor and a second light-emitting control transistor. A gate
electrode of the first light-emitting control transistor is
configured to receive a light-emitting control signal, a first
electrode thereof is configured to receive the first power source
voltage, and a second electrode thereof is connected to the first
electrode of the driving transistor. A gate electrode of the second
light-emitting control transistor is configured to receive the
light-emitting control signal, a first electrode thereof is
connected to the second electrode of the driving transistor, and a
second electrode thereof is connected to the light-emitting
element.
[0012] In a possible embodiment of the present disclosure, the
first compensating transistor and the second compensating
transistor are both P-type transistors.
[0013] In a possible embodiment of the present disclosure, the data
writing transistor is a P-type transistor.
[0014] In a possible embodiment of the present disclosure, the
first light-emitting control transistor and the second
light-emitting control transistor are both P-type transistors.
[0015] In another aspect, the present disclosure provides in some
embodiments a pixel driving method applied to the above-mentioned
pixel driver circuit, including steps of: at a threshold
compensation stage of each display period, enabling, by a threshold
compensation unit, a gate electrode of a driving transistor to
receive a reference voltage, and enabling a second electrode of the
driving transistor to be connected to a resetting voltage line, so
as to enable the driving transistor to be turned on and discharged
toward a start voltage line until the driving transistor is turned
off; at a data writing stage of each display period, writing, by a
data writing unit, a data voltage into the gate electrode of the
driving transistor; and at a light-emitting stage of each display
period, enabling, by a light-emitting control unit, a first
electrode of the driving transistor to be driven at a first power
source voltage, and enabling the second electrode of the driving
transistor to be electrically connected to a light-emitting
element, so as to enable the driving transistor to be turned on and
drive the light-emitting element to emit light. A total amount of
charges stored in a first storage capacitor and charges stored in a
second storage capacitor at the threshold compensation stage is
equal to that at the data writing stage. An amount of charges
stored in the first storage capacitor at the data writing stage is
equal to an amount of charges stored in the first storage capacitor
at the light-emitting control stage.
[0016] In a possible embodiment of the present disclosure, within
each display period, the threshold compensation stage further
includes a resetting stage. The pixel driving method further
includes, at the resetting stage of each display period, enabling,
by the threshold compensation unit, the gate electrode of the
driving transistor to receive the reference voltage and enabling
the second electrode of the driving transistor to be electrically
connected to the resetting voltage line, and enabling, by the
light-emitting control unit, the first electrode of the driving
transistor to receive the first power source voltage and enabling
the second electrode of the driving transistor to be connected to
the light-emitting element. The driving transistor is in an
amplified state or a saturation state at the resetting stage.
[0017] In yet another aspect, the present disclosure provides in
some embodiments a pixel driving method applied to the
above-mentioned pixel driver circuit, including steps of: at a
threshold compensation stage of each display period, enabling a
light-emitting control signal and a scanning signal to be turn-off
signals, and enabling a resetting control signal to be a turn-on
signal, so as to enable a resetting voltage line to output a
resetting voltage at a low level, enable a first light-emitting
control transistor and a second light-emitting control transistor
to be turned off, enable a first compensating transistor and a
second compensating transistor to be turned on, and enable charges
at a connection node between a first storage capacitor and a second
storage capacitor to be discharged toward the resetting voltage
line through a driving transistor and the first compensating
transistor until a potential at a source electrode of the driving
transistor is sufficient low to turn off the driving transistor; at
a data writing stage of each display period, enabling the
light-emitting control signal and the resetting control signal to
be turn-off signals, and enabling the scanning signal to be a
turn-on signal, so as to enable the first light-emitting control
transistor and the second light-emitting control transistor to be
turned off, enable the first compensating transistor and the second
compensating transistor to be turned off, enable a data writing
transistor to be turned on to write a data voltage into a gate
electrode of the driving transistor, and enable the connection node
between the first storage capacitor and the second storage
capacitor to be in a floating state, a total amount of the charges
stored in the first storage capacitor and the charges stored in the
second storage capacitor at the threshold compensation stage being
equal to that at the data writing stage; and at a light-emitting
stage of each display period, enabling the scanning signal and the
resetting control signal to be turn-off signals to turn off the
first compensating transistor, the second compensating transistor
and the data writing transistor, and enabling the light-emitting
control signal to be a turn-on signal, so as to enable the first
light-emitting control transistor and the second light-emitting
control transistor to be turned on, enable a light-emitting element
to be electrically connected to a second electrode of the driving
transistor, enable a first power source voltage to be written into
a connection node among a first electrode of the driving
transistor, the first storage capacitor and the second storage
capacitor, enable a first end of the second storage capacitor to
receive the first power source voltage, and enable a node between
the first storage capacitor and the gate electrode of the driving
transistor to be in a floating stage, an amount of the charges
stored in the first storage capacitor at the data writing stage
being equal to an amount of the charges stored in the first storage
capacitor at the light-emitting control stage so that a current
flowing through the driving transistor at the light-emitting stage
is merely associated with the data voltage, a capacitance of the
first storage capacitor and a capacitance of the second storage
capacitor.
[0018] In a possible embodiment of the present disclosure, within
each display period, the threshold compensating stage further
includes a resetting stage, and the pixel driving method further
includes, at the resetting stage of each display period, enabling
the light-emitting control signal and the resetting control signal
to be turn-on signals, and enabling the scanning signal to a
turn-off signal, so as to enable the first light-emitting control
transistor and the second light-emitting control transistor to be
turned on, enable the first compensating transistor and the second
compensating transistor to be turned on, enable the data writing
transistor to be turned off, enable the light-emitting element to
be connected to the second electrode of the driving transistor,
enable the resetting voltage to be written into the second
electrode of the driving transistor, and enable the driving
transistor to be in an amplified state or a saturation state.
[0019] In a possible embodiment of the present disclosure, in the
case that the light-emitting element includes an OLED, an anode of
which is connected to the second electrode of the driving
transistor through the light-emitting control unit, and a cathode
of which is configured to receive a second power source voltage, at
the resetting stage, a difference between the resetting voltage
from the resetting voltage line and the second power source voltage
is smaller than an on-state threshold voltage of the OLED.
[0020] In still yet another aspect, the present disclosure provides
in some embodiments a display panel including the above-mentioned
pixel driver circuit.
[0021] In still yet another aspect, the present disclosure provides
in some embodiments a display device including the above-mentioned
display panel.
[0022] According to the pixel driver circuit, the pixel driving
method, the display panel and the display device in the embodiments
of the present disclosure, through the control over the amount of
the charges stored in the first storage capacitor and the second
storage capacitor at the threshold compensation stage and the
light-emitting stage, the current flowing through the driving
transistor for driving the light-emitting element at the
light-emitting stage may be independent of a threshold voltage and
a power source voltage of the driving transistor, and instead it
may be merely associated with the data voltage, the reference
voltage, the capacitance of the first storage capacitor and the
capacitance of the second storage capacitor. In the case that the
data voltage is equal to the reference voltage, it is able to
output different currents by changing the capacitance of the first
storage capacitor and the capacitance of the second storage
capacitor, and compress the data at different compression ratios,
thereby to increase the data driving voltage range of the driver
IC.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic view showing a pixel driver circuit
according to at least one embodiment of the present disclosure;
[0024] FIG. 2 is another schematic view showing the pixel driver
circuit according to at least one embodiment of the present
disclosure;
[0025] FIG. 3 is yet another schematic view showing the pixel
driver circuit according to at least one embodiment of the present
disclosure;
[0026] FIG. 4A is a schematic view showing the pixel driver circuit
in FIG. 3 in the case that a threshold compensation unit includes a
first compensating transistor and a second compensating
transistor;
[0027] FIG. 4B is a schematic view showing the pixel driver circuit
in FIG. 3 in the case that a data writing unit includes a data
writing transistor;
[0028] FIG. 4C is a schematic view showing the pixel driver circuit
in FIG. 3 in the case that a light-emitting control unit includes a
first light-emitting control transistor and a second light-emitting
control transistor;
[0029] FIG. 5 is a circuit diagram of the pixel driver circuit
according to one embodiment of the present disclosure;
[0030] FIG. 6 is a sequence diagram of the pixel driver circuit in
FIG. 5;
[0031] FIG. 7 is a flow chart of a pixel driving method according
to at least one embodiment of the present disclosure; and
[0032] FIG. 8 is another flow chart of the pixel driving method
according to at least one embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0033] In order to make the objects, the technical solutions and
the advantages of the present disclosure more apparent, the present
disclosure will be described hereinafter in a clear and complete
manner in conjunction with the drawings and embodiments. Obviously,
the following embodiments merely relate to a part of, rather than
all of, the embodiments of the present disclosure, and based on
these embodiments, a person skilled in the art may, without any
creative effort, obtain the other embodiments, which also fall
within the scope of the present disclosure.
[0034] As shown in FIG. 1, the present disclosure provides in some
embodiments a pixel driver circuit which includes a driving
transistor MDT, a first storage capacitor C1, a second storage
capacitor C2, a threshold compensation unit 11, a data writing unit
12 and a light-emitting control unit 13. A gate electrode of the
driving transistor MDT is connected to a first end of the first
storage capacitor C1, and a first electrode thereof is connected to
a second end of the first storage capacitor C1. A first end of the
second storage capacitor C2 is configured to receive a first power
source voltage V1, and a second end thereof is connected to the
second end of the first storage capacitor C1. The threshold
compensation unit 11 is configured to, at a threshold compensation
stage of each display period, control the gate electrode of the
driving transistor MDT to receive a reference voltage Vref and
enable a second electrode of the driving transistor MDT to be
electrically connected to a resetting voltage line for outputting
the resetting voltage Vini, so as to enable the driving transistor
MDT to be turned on and discharge toward the resetting voltage line
until the driving transistor MDT is turned off. The data writing
unit 12 is configured to, at a data writing stage of each display
period, write a data voltage SD into the gate electrode of the
driving transistor MDT. The light-emitting control unit 13 is
configured to, at a light-emitting stage of each display period,
control the first electrode of the driving transistor MDT to
receive the first power source voltage V1 and enable the second
electrode of the driving transistor MDT to be eclectically
connected to a light-emitting element LE, so as to enable the
driving transistor MDT to be turned on and drive the light-emitting
element LE to emit light. A total amount of charges stored in the
first storage capacitor C1 and a total amount of charges stored in
the second storage capacitor C2 at the threshold compensation stage
is equal to those at the data writing stage. An amount of charges
stored in the first storage capacitor C1 at the data writing stage
is equal to an amount of charges stored in the first storage
capacitor C1 at the light-emitting control stage.
[0035] In FIG. 1, the driving transistor MDT is a P-type
transistor. At this time, the first electrode of the driving
transistor MDT is a source electrode and a second electrode thereof
is a drain electrode. During the implementation, the driving
transistor MDT may also be an N-type transistor.
[0036] According to the pixel driver circuit in the embodiments of
the present disclosure, through the control over the amount of the
charges stored in the first storage capacitor and the amount of the
charges stored in the second storage capacitor at the threshold
compensation stage and the light-emitting stage, a current flowing
through the driving transistor for driving the light-emitting
element at the light-emitting stage may be independent of a
threshold voltage of the driving transistor and a power source
voltage, and instead it may be merely associated with the data
voltage, the reference voltage, a capacitance of the first storage
capacitor and a capacitance of the second storage capacitor. In the
case that the data voltage and the reference voltage are the same,
it is able to output different currents by changing the capacitance
of the first storage capacitor and the capacitance of the second
storage capacitor, and compress the data at different compression
ratios, thereby to raise the data driving voltage range of a driver
IC.
[0037] In the embodiments of eh present disclosure, all the
transistors may be TFTs, or field effect transistors (FETs) or any
other elements having an identical characteristic. In order to
differentiate two electrodes other than the gate electrode from
each other, one of them may be called as a source electrode and the
other may be called as a drain electrode. In addition, depending on
its characteristic, the transistor may be an N-type or a P-type
transistor. For the driver circuit in the embodiments of the
present disclosure, all the transistors are P-type transistors, and
of course, N-type transistors may also be adopted, which also fall
within the scope of the present disclosure.
[0038] In a possible embodiment of the present disclosure, within
each display period, the threshold compensation stage further
includes a resetting stage. The threshold compensation unit is
further configured to, at the resetting stage, control the gate
electrode of the driving transistor to receive the reference
voltage and enable the second electrode of the driving transistor
to be connected to the resetting voltage line. The light-emitting
control unit is further configured to, at the resetting stage,
control the first electrode of the driving transistor to receive
the first power source voltage and enable the second electrode of
the driving transistor to be electrically connected to the
light-emitting element. The driving transistor is in an amplified
state or a saturation state at the resetting stage.
[0039] In the embodiments of the present disclosure, in the case
that the driving transistor is in the amplified state or the
saturation state at the resetting stage, it is able to ensure a
large current flowing through the driving transistor, so as to
eliminate or reduce the characteristic drift of the driving
transistor due to a stress at a small current in the case that a
display panel is switched from a state where a low-brightness image
is displayed for a long time period at the small current to a state
where a high-brightness image is displayed at a large current,
thereby to eliminate or attenuate a brightness trailing phenomenon
due to the characteristic drift in the case that the display panel
is switched from displaying a black image to displaying a white
image.
[0040] In addition, in a possible embodiment of the present
disclosure, at the resetting stage, the threshold compensation unit
is further configured to, at the resetting stage, control the gate
electrode of the driving transistor (i.e., the first end of the
first storage capacitor) to receive the reference voltage, so as to
enable the second electrode of the driving transistor (i.e., the
second end of the first storage capacitor) to be electrically
connected to the resetting voltage line, thereby to initialize a
voltage across the first storage capacitor and prevent the writing
of a current-frame signal from being adversely affected by a
previous-frame signal.
[0041] In a possible embodiment of the present disclosure, the
driving transistor may operate at a saturation zone at the
resetting stage (i.e., the driving transistor is in the saturation
state at the resetting stage). At this time, it is able to maximize
the current flowing through the driving transistor.
[0042] To be specific, as shown in FIG. 2, in the pixel driver
circuit in the embodiments of the present disclosure, the threshold
compensation unit 11 is configured to receive a resetting control
signal Reset, the data writing unit 12 is configured to receive a
scanning signal Gate, and the light-emitting control unit 13 is
configured to receive a light-emitting control signal EM. The
threshold compensation unit 11 is configured to, at the resetting
stage and the threshold compensation stage of each display period,
enable the gate electrode of the driving transistor MDT to receive
the reference voltage Vref and enable the second electrode of the
driving transistor MDT to receive the resetting voltage Vini under
the control of the resetting control signal Reset. The data writing
unit 12 is configured to, at the data writing stage of each display
period, write the data voltage SD into the gate electrode of the
driving transistor MDT under the control of the scanning signal
Gate. The light-emitting control unit 13 is configured to, at the
light-emitting stage of each display period, enable the first
electrode of the driving transistor MDT to receive the first power
source voltage V1 and enable the second electrode of the driving
transistor MDT to be electrically connected to the light-emitting
element LE under the control of the light-emitting control signal
EM.
[0043] To be specific, as shown in FIG. 3, on the basis of the
pixel driver circuit in FIG. 2, the light-emitting element may
include an OLED D1, an anode of which is connected to the second
electrode of the driving transistor MDT through the light-emitting
control unit 13, and a cathode of which is configured to receive a
second power source voltage V2.
[0044] At the resetting stage, a difference between the resetting
voltage Vini from the resetting voltage line and the second power
source voltage V2 is smaller than an on-state threshold voltage of
the OLED D1. In this way, it is able to ensure the OLED D1 not to
emit light at the resetting stage, thereby to improve the display
quality in a dark state and improve the contrast.
[0045] To be specific, the threshold compensation unit includes a
first compensating transistor and a second compensating transistor.
A gate electrode of the first compensating transistor is configured
to receive a resetting control signal, a first electrode thereof is
connected to the second electrode of the driving transistor, and a
second electrode thereof is connected to the resetting voltage
line. A gate electrode of the second compensating transistor is
configured to receive the resetting control signal, a first
electrode thereof is connected to the gate electrode of the driving
transistor, and a second electrode thereof is configured to receive
the reference voltage.
[0046] To be specific, the data writing unit includes a data
writing transistor, a gate electrode of which is configured to
receive the scanning signal, a first electrode of which is
connected to the gate electrode of the driving transistor, and a
second electrode of which is configured to receive the data
voltage.
[0047] To be specific, the light-emitting control unit includes a
first light-emitting control transistor and a second light-emitting
control transistor. A gate electrode of the first light-emitting
control transistor is configured to receive the light-emitting
control signal, a first electrode thereof is configured to receive
the first power source voltage, and a second electrode thereof is
connected to the first electrode of the driving transistor. A gate
electrode of the second light-emitting control transistor is
configured to receive the light-emitting control signal, a first
electrode thereof is connected to the second electrode of the
driving transistor, and a second electrode thereof is connected to
the light-emitting element.
[0048] As shown in FIG. 4A, on the basis of the pixel driver
circuit in FIG. 3, the threshold compensation unit 11 includes a
first compensating transistor M1 and a second compensating
transistor M2, which are both P-type transistors. A gate electrode
of the first compensating transistor M1 is configured to receive
the resetting control signal Reset, a source electrode thereof is
connected to the drain electrode of the driving transistor MDT, and
a drain electrode thereof is connected to the resetting voltage
line for outputting the resetting voltage Vini. A gate electrode of
the second compensating transistor M2 is configured to receive the
resetting control signal Reset, a source electrode thereof is
connected to the gate electrode of the driving transistor MDT, and
a drain electrode thereof is configured to receive the reference
voltage Vref.
[0049] As shown in FIG. 4B, on the basis of the pixel driver
circuit in FIG. 3, the data writing unit 12 includes a data writing
transistor M3, which is a P-type transistor.
[0050] A gate electrode of the data writing transistor M3 is
configured to receive the scanning signal Gate, a source electrode
thereof is connected to the gate electrode of the driving
transistor MDT, and a drain electrode thereof is configured to
receive the data voltage SD.
[0051] As shown in FIG. 4C, on the basis of the pixel driver
circuit in FIG. 3, the light-emitting control unit includes a first
light-emitting control transistor M4 and a second light-emitting
control transistor M5. A gate electrode of the first light-emitting
control transistor M4 is configured to receive the light-emitting
control signal EM, a source electrode thereof is configured to
receive the first power source voltage V1, and a drain electrode
thereof is connected to the source electrode of the driving
transistor MDT. A gate electrode of the second light-emitting
control transistor M5 is configured to receive the light-emitting
control signal EM, a source electrode thereof is connected to the
drain electrode of the driving transistor MDT, and a drain
electrode thereof is connected to the anode of the OLED D1.
[0052] The pixel driver circuit will be described hereinafter in
conjunction with a specific embodiment.
[0053] As shown in FIG. 5, the pixel driver circuit includes the
driving transistor MDT, the first storage capacitor C1, the second
storage capacitor C2, the threshold compensation unit, the data
writing unit and the light-emitting control unit. A gate electrode
of the driving transistor MDT is connected to a first end of the
first storage capacitor C1, and a source electrode thereof is
connected to a second end of the first storage capacitor C1. A
first end of the second storage capacitor C2 is configured to
receive a high voltage VDD, and a second end thereof is connected
to the second end of the first storage capacitor C1.
[0054] The threshold compensation unit includes a first
compensating transistor M1 and a second compensating transistor M2.
A gate electrode of the first compensating transistor M1 is
configured to receive the resetting control signal Reset, a source
electrode thereof is connected to a drain electrode of the driving
transistor MDT, and a drain electrode thereof is connected to the
resetting voltage line for outputting the resetting voltage Vini. A
gate electrode of the second compensating transistor M2 is
configured to receive the resetting control signal Reset, a source
electrode thereof is connected to the gate electrode of the driving
transistor MDT, and a drain electrode thereof is configured to
receive the reference voltage Vref.
[0055] The data writing unit includes a data writing transistor M3,
a gate electrode of which is configured to receive the scanning
signal Gate, a source electrode of which is connected to the gate
electrode of the driving transistor MDT, and a drain electrode of
which is configured to receive the data voltage SD.
[0056] The light-emitting control unit includes a first
light-emitting control transistor M4 and a second light-emitting
control transistor M5. A gate electrode of the first light-emitting
control transistor M4 is configured to receive the light-emitting
control signal EM, a source electrode thereof is connected to
receive the high voltage VDD, and a drain electrode thereof is
connected to the source electrode of the driving transistor MDT. A
gate electrode of the second light-emitting control transistor M5
is configured to receive the light-emitting control signal EM, a
source electrode thereof is connected to the drain electrode of the
driving transistor MDT, and a drain electrode thereof is connected
to the anode of the OLED D1. The cathode of the OLED D1 is
configured to receive a low voltage VSS. In FIG. 5, a connection
node between the first storage capacitor C1 and the second storage
capacitor C2 is a node A.
[0057] In FIG. 5, all the transistors are P-type transistors, and
during the actual operation, these transistors may also be N-type
transistors.
[0058] As shown in FIG. 6, during the operation of the pixel driver
circuit in FIG. 5, at the resetting stage T1, EM is a low-voltage
turn-on signal, Reset is a low-voltage turn-on signal, and Gate is
a high-voltage turn-off signal. M4 and M5 under the control of EM
are both turned on, and M1 and M2 under the control of Reset are
turned on too. The anode of D1 is electrically connected to the
drain electrode of MDT, so Vini is written into the drain electrode
of MDT and the anode of D1, and thereby a potential at the anode of
D1 is reset to Vini. In addition, a difference between Vini and VSS
is preferably smaller than an on-state threshold voltage of D1, so
as to ensure that D1 does not emit light at this time, thereby to
improve the display quality in the dark state and improve the
contrast. VDD is written into the source electrode of MDT, and
meanwhile Vref is written into the gate electrode of MDT. A
difference between Vref and VDD is just Vgs of MDT, so it is able
to ensure a large current flowing through MDT, so as to eliminate
or reduce the characteristic drift of MDT due to a stress at a
small current in the case that a display panel is switched from a
state where a low-brightness image is displayed for a long time
period at the small current to a state where a high-brightness
image is displayed at a large current, thereby to eliminate or
attenuate a brightness trailing phenomenon due to the
characteristic drift in the case that the display panel is switched
from displaying a black image to displaying a white image. At this
stage, the large current flowing through MDT depends on Vref and
Vini. MDT may operate at an amplified zone or a saturation zone.
Theoretically, MDT prefers to operate at the saturation zone, and
at this time, it is able to maximize the current flowing through
MDT.
[0059] At the resetting stage T1, the voltage across C1 may be
reset, so as to prevent the writing of a current-frame signal from
being adversely affected by a previous-frame signal.
[0060] At the threshold compensation stage T2, EM and Gate are both
high-voltage turn-off signals, and Reset is a low-voltage turn-on
signal. M4 and M5 under the control of EM are turned off, and M1
and M2 under the control of Reset are maintained in an on state. In
this way, charges stored at a connection node (i.e., node A in FIG.
3) between C1 and C2 may be discharged through MDT and M1 toward
the resetting voltage line for outputting a low-potential Vini
until a potential at the source electrode of MDT is sufficient low
to turn off MDT. At this time, for MDT, Vgs-Vth=0. Because Vg=Vref,
Vs=Vg-Vth=Vref-Vth. In other words, a voltage across C1 is just
equal to the threshold voltage Vth of MDT.
[0061] At the data writing stage T3, EM and Reset are both
high-voltage turn-off signals, and Gate is a low-voltage turn-on
signal. M4 and M5 under the control of EM are both turned off, and
M1 and M2 under the control of Reset are turned off too. In
addition, M3 under the control of Gate is in the on state, so SD is
written into the gate electrode of MDT, i.e., a connection node
between C1 and the gate electrode of MDT. For a series circuit
consisting of C1 and C2, a voltage at a connection node between C1
and C2 is in a floating state, and a total amount of charges stored
in C1 and C2 at the data writing stage T3 is equal to a total
amount of charges stored in C1 and C2 at the threshold compensation
stage T2. Presumed that a voltage at the connection node between C1
and C2 is X, a total amount of the charges stored in C1 and C2
before the change is equal to
(Vref-Vth-Vref)*C1+[VDD-(Vref-Vth)]*C2, and a total amount of the
charges stored in C1 and C2 after the change is equal to
(X-SD)*C1+(VDD-X)*C2. Based on a principle where the total amount
of the charges remain unchanged before and after the change, it may
be deduced that X=(Vref*C2-SD*C1)/(C2-C1)-Vth.
[0062] At the light-emitting stage T4, Gate and Reset are both
high-voltage turn-off signals, so M1, M2 and M3 are all in off
state. EM is a low-voltage turn-on signal, so M4 and M5 are turned
on. In the case that M5 is turned on, the anode of D1 is
electrically connected to the drain electrode of MDT, and in the
case that M3 is turned on, VDD is written into the source electrode
of MDT and the connection node between C1 and C2. Because the first
end of C2 is configured to receive VDD, the capacitances of C1 and
C2 may not be adversely affected by the change in the potential at
the connection node between C1 and C2. At this time, the connection
node between C1 and the gate electrode of MDT is in a floating
state. Due to C1, the potential at the connection node between C1
and the gate electrode of MDT may change along with the potential
at the connection node between C1 and C2, and before and after the
change, the amount of the charges stored in C1 may remain unchanged
(i.e., the amount of the charges stored in C1 at the data writing
stage T3 is equal to that at the light-emitting stage T4).
[0063] The amount of the charges stored in C1 before the change is
equal to (X-Vref)*C1=[(Vref*C2-SD*C1)/(C2-C1)-Vth-Vref]*C1, and the
amount of the charges stored in C1 after the change (presumed that
a potential at the gate electrode of MDT after the change is Y) is
equal to (VDD-Y)*C1. Based on a principle of charge conservation,
it may be deduced that Y=VDD+Vth+C2*(SD-Vref)/(C2-C1). Because MDT
is in the saturation zone, it may be deduced in accordance with a
formula for calculating a current flowing through a transistor in
the saturation zone that Ids=1/2*K*(Vgs-Vth)
2=1/2*K*(VDD+Vth+C2*(SD-Vref)/(C2-C1)-VDD-Vth)
2=1/2*K*(C2*(SD-Vref)/(C2-C1))2, where Ids represents a
drain-to-source current in the case that MDT operates in the
saturation zone, K represents a current parameter and has a
relatively stable value, i.e., it may be a constant, and C2/(C2-C1)
represents a capacitance and may also be considered as a constant.
In this regard, a value of Ids merely depends on the data voltage
SD and the reference voltage Vref Vref is a direct current voltage
signal, so the value of Ids is merely associated with the data
voltage SD. Hence, for the circuit structure of the pixel driver
circuit in FIG. 3, it is able to not only compensate for the
threshold voltage of the driving transistor MDT, but also
compensate for an IR drop on the power source signal VDD. In
addition, it is able to able output different currents in
accordance with a ratio of C2/(C2-C1) in the case of an identical
data voltage, thereby to compress data at different compression
ratios.
[0064] As shown in FIG. 7, the present disclosure further provides
in some embodiments a pixel driving method applied to the
above-mentioned pixel driver circuit, including: a threshold
compensation step S1 of, at a threshold compensation stage of each
display period, controlling, by a threshold compensation unit, a
gate electrode of a driving transistor to receive a reference
voltage, and enabling a second electrode of the driving transistor
to be electrically connected to a resetting voltage line, so as to
enable the driving transistor to be turned on and discharge toward
a start voltage line until the driving transistor is turned off; a
data writing step S2 of, at a data writing stage of each display
period, writing, by a data writing unit, a data voltage into the
gate electrode of the driving transistor; and a light emitting step
S3 of, at a light-emitting stage of each display period, enabling,
by a light-emitting control unit, a first electrode of the driving
transistor to be driven at a first power source voltage, and
enabling the second electrode of the driving transistor to be
electrically connected to a light-emitting element, so as to enable
the driving transistor to be turned on and drive the light-emitting
element to emit light. A total amount of charges stored in a first
storage capacitor and charges stored in a second storage capacitor
at the threshold compensation stage is equal to that at the data
writing stage. An amount of charges stored in the first storage
capacitor at the data writing stage is equal to an amount of
charges stored in the first storage capacitor at the light-emitting
control stage.
[0065] According to the pixel driving method in the embodiments of
the present disclosure, through the control over the amount of the
charges stored in the first storage capacitor and the second
storage capacitor at the threshold compensation stage and the
light-emitting stage, the current flowing through the driving
transistor for driving the light-emitting element at the
light-emitting stage may be independent of a threshold voltage of
the driving transistor and a power source voltage, and instead it
may be merely associated with the data voltage, the reference
voltage, the capacitance of the first storage capacitor and the
capacitance of the second storage capacitor. In the case that the
data voltage and the reference voltage are the same, it is able to
output different currents by changing the capacitance of the first
storage capacitor and the capacitance of the second storage
capacitor, and compress the data at different compression
ratios.
[0066] In a possible embodiment of the present disclosure, within
each display period, the threshold compensation stage further
includes a resetting stage. As shown in FIG. 8, the pixel driving
method further includes a resetting step S0 of, at the resetting
stage of each display period, controlling, by the threshold
compensation unit, the gate electrode of the driving transistor to
receive the reference voltage and enabling the second electrode of
the driving transistor to be electrically connected to the
resetting voltage line, and enabling, by the light-emitting control
unit, the first electrode of the driving transistor to receive the
first power source voltage and enabling the second electrode of the
driving transistor to be connected to the light-emitting element.
The driving transistor is in an amplified state or a saturation
state at the resetting stage.
[0067] In the embodiments of the present disclosure, in the case
that the driving transistor is in the amplified state or the
saturation state at the resetting stage, it is able to ensure a
large current flowing through the driving transistor, so as to
eliminate or reduce the characteristic drift of the driving
transistor due to a stress at a small current in the case that a
display panel is switched from a state where a low-brightness image
is displayed for a long time period at the small current to a state
where a high-brightness image is displayed at a large current,
thereby to eliminate or attenuate a brightness trailing phenomenon
due to the characteristic drift in the case that the display panel
is switched from displaying a black image to displaying a white
image.
[0068] In addition, in a possible embodiment of the present
disclosure, at the resetting stage, the threshold compensation unit
is further configured to control, at the resetting stage, the gate
electrode of the driving transistor (i.e., the first end of the
first storage capacitor) to receive the reference voltage, so as to
enable the second electrode of the driving transistor (i.e., the
second end of the first storage capacitor) to be electrically
connected to the resetting voltage line, thereby to initialize a
voltage across the first storage capacitor and prevent the writing
of a current-frame signal from being adversely affected by a
previous-frame signal.
[0069] The present disclosure further provides in some embodiments
a pixel driving method which includes steps of: at a threshold
compensation stage of each display period, enabling a
light-emitting control signal and a scanning signal to be turn-off
signals, and enabling a resetting control signal to be a turn-on
signal, so as to enable a resetting voltage signal to output a
resetting voltage at a low level, enable a first light-emitting
control transistor and a second light-emitting control transistor
to be turned off, enable a first compensating transistor and a
second compensating transistor to be turned on, and enable charges
in the connection node between a first storage capacitor and a
second storage capacitor to be discharged toward the resetting
voltage line through a driving transistor and the first
compensating transistor until a potential at a source electrode of
the driving transistor is sufficient low to turn off the driving
transistor; at a data writing stage of each display period,
enabling the light-emitting control signal and the resetting
control signal to be turn-off signals, and enabling the scanning
signal to be a turn-on signal, so as to enable the first
light-emitting control transistor and the second light-emitting
control transistor to be turned off, enable the first compensating
transistor and the second compensating transistor to be turned off,
enable a data writing transistor to be turned on to write a data
voltage into a gate electrode of the driving transistor, and enable
the connection node between the first storage capacitor and the
second storage capacitor to be in a floating state, a total amount
of the charges stored in the first storage capacitor and the
charges stored in the second storage capacitor at the threshold
compensation stage being equal to that at the data writing stage;
and at a light-emitting stage of each display period, enabling the
scanning signal and the resetting control signal to be turn-off
signals to turn off the first compensating transistor, the second
compensating transistor and the data writing transistor, and
enabling the light-emitting control signal to be a turn-on signal,
so as to enable the first light-emitting control transistor and the
second light-emitting control transistor to be turned on, enable a
light-emitting element to be electrically connected to a second
electrode of the driving transistor, enable a first power source
voltage to be written into a connection node among a first
electrode of the driving transistor, the first storage capacitor
and the second storage capacitor, enable a first end of the second
storage capacitor to receive the first power source voltage, and
enable a connection node between the first storage capacitor and
the gate electrode of the driving transistor to be in a floating
stage, an amount of the charges stored in the first storage
capacitor at the data writing stage being equal to an amount of the
charges stored in the first storage capacitor at the light-emitting
control stage so that a current flowing through the driving
transistor at the light-emitting stage is merely associated with
the data voltage, a capacitance of the first storage capacitor and
a capacitance of the second storage capacitor.
[0070] In a possible embodiment of the present disclosure, within
each display period, the threshold compensating stage further
includes a resetting stage. The pixel driving method further
includes, at the resetting stage of each display period, enabling
the light-emitting control signal and the resetting control signal
to be turn-on signals, and enabling the scanning signal to a
turn-off signal, so as to enable the first light-emitting control
transistor and the second light-emitting control transistor to be
turned on, enable the first compensating transistor and the second
compensating transistor to be turned on, enable the data writing
transistor to be turned off, enable the light-emitting element to
be connected to the second electrode of the driving transistor,
enable the resetting voltage to be written into the second
electrode of the driving transistor, and enable the driving
transistor to be in an amplified state or a saturation state. It is
able to ensure a large current flowing through the driving
transistor, so as to eliminate or reduce the characteristic drift
of the driving transistor due to a stress at a small current in the
case that a display panel is switched from a state where a
low-brightness image is displayed for a long time period at the
small current to a state where a high-brightness image is displayed
at a large current, thereby to eliminate or attenuate a brightness
trailing phenomenon due to the characteristic drift in the case
that the display panel is switched from displaying a black image to
displaying a white image.
[0071] In addition, in a possible embodiment of the present
disclosure, at the resetting stage, the threshold compensation unit
is further configured to enable, at the resetting stage, the gate
electrode of the driving transistor (i.e., the first end of the
first storage capacitor) to receive the reference voltage, so as to
enable the second electrode of the driving transistor (i.e., the
second end of the first storage capacitor) to be electrically
connected to the resetting voltage line, thereby to initialize a
voltage across the first storage capacitor and prevent the writing
of a current-frame signal from being adversely affected by a
previous-frame signal.
[0072] In a possible embodiment of the present disclosure, in the
case that the light-emitting element includes an OLED, an anode of
which is connected to the second electrode of the driving
transistor through the light-emitting control unit, and a cathode
of which is configured to receive a second power source voltage, at
the resetting stage, a difference between the resetting voltage
from the resetting voltage line and the second power source voltage
is smaller than an on-state threshold voltage of the OLED, so as to
ensure the OLED not emitting light at the resetting stage.
[0073] The present disclosure further provides in some embodiments
a display panel including the above-mentioned pixel driver
circuit.
[0074] The present disclosure further provides in some embodiments
a display device including the above-mentioned display panel.
[0075] The above are merely the preferred embodiments of the
present disclosure. Obviously, a person skilled in the art may make
further modifications and improvements without departing from the
spirit of the present disclosure, and these modifications and
improvements shall also fall within the scope of the present
disclosure.
* * * * *